Process and device for aiding aerial navigation

ABSTRACT

The invention relates to processes for aiding aerial navigation. According to the invention, there is proposed a process for aiding aerial navigation, using a flight management system (FMS) which carriers out a dialogue with the pilot by means of several interfaces which include at least one display screen. The flight management system displays on the screen a time-graduated abscissa axis, an altitude-graduated ordinate axis, and, in this system of axes, a plot representing a theoretical path of an aircraft. The flight management system scrolls the time axis and optionally the altitude axis in such a way that the origin of the axes at the instant of display represents, along the abscissa, the time at the instant of display and along the ordinate the altitude of the aircraft at this instant. The pilot thus obtains a better assessment of the time management of the flight.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to processes and devices for assisting aerialnavigation.

2. Discussion of the Background

In general, it is known that in aerodynes (aircraft, helicopters, etc.)of modern design, the pilot must carry out a dialogue with a flightmanagement system, this being a computer on board the aerodyne (we shallsubsequently speak of an aircraft) for assisting the pilot in a numberof operations. These operations are mainly operations for defining theflight plan before take-off, piloting (manual or automatic) operationsduring take-off and landing, aerial navigation operations (pathcalculations, etc.), systematic monitoring operations while cruising orwhen approaching an airport.

The flight management system operates on the basis of data entered bythe pilot, data supplied by sensors distributed throughout the aircraft,and possibly digital data transmitted by radio from the ground or fromother aircraft or even satellites.

The dialogue between the flying crew and the flight management system iscarried out mainly by means of at least three interfaces, viz.:

a navigation display on which is represented the plot of the desiredcourse of the aircraft, that is to say a graphical representation of theflight plan of the aircraft and the situation of the aircraft withinthis plan (in two dimensions);

a primary flight display which depicts, on the one hand, an artificialhorizon which tilts as the aircraft tilts, and, on the other hand, anindication of the longitudinal attitude of the aircraft, and otheruseful flying indications;

a flight control unit having manual controls for selecting settings suchas the desired heading of the aircraft;

and finally a keyboard/display console, termed the MCDU ("MultipurposeControl Display Unit"), this being a data display and input consoleallowing the flying crew to enter data into the flight management systemand to read information forwarded by the flight management system on thebasis of the data entered.

One of the tasks of the pilot consists in calculating, checking andpossibly modifying the flight plan of the aircraft, that is to say theessential elements of the course which he is to follow, especiallytransits above characteristic points called "waypoints".

The flight plan comprises two components: lateral flight plan whichdefines the waypoints by their longitudes and latitudes, and verticalflight plan which defines the cruising altitudes and the rates of climband descent during changes of altitude. These elements of the verticalflight plan are defined with respect to the waypoints.

French patent Application 92 03 643 filed on Mar. 26, 1992 proposed aprocess for assisting pilotage in which the vertical flight plan isdisplayed separately from the lateral flight plan on a viewing screen,that is to say instead of displaying the vertical flight plan elementsin the form of symbolic or textual indications on the lateral flightplan, a vertical flight plan is displayed separately in the form of aplot in a system with two axes, viz. the distances along the abscissa(with indications of the waypoints) and the altitudes along theordinate.

In such a process, the plot can also comprise a symbol representing theaircraft, which moves with respect to the graduations of the abscissaand of the ordinate as the aircraft advances, and, advantageously,arrangements may even be made for the symbol of the aircraft to remainfixed along the abscissa and for the abscissa scale to scroll along withthe advance of the aircraft; thus, it is chiefly that part of thejourney still to be made which appears on the screen, and optionallyalso part of the path that has already been travelled. The symbol of theaircraft can also remain fixed along the ordinate and in this case thealtitude scale would scroll as the aircraft climbs or descends.

The vertical flight plan can be depicted on the navigation display andcan occupy either the whole of the screen (the pilot then chooses todisplay either the vertical flight plan or the lateral flight plan) orone part of the screen, the other part being assigned to the lateralflight plan; the pilot can then see the lateral flight plan and thevertical flight plan at the same time.

SUMMARY OF THE INVENTION

It has been realized that it may be advantageous for the vertical flightplan to be available to the pilot in a different form.

According to the invention, there is proposed a process for aidingaerial navigation, using a flight management system (FMS) which carriesout a dialogue with the pilot by means of several interfaces whichinclude at least one display screen, characterized in that the flightmanagement system displays on the screen a time-graduated abscissa axis,an altitude-graduated ordinate axis, and, in this system of axes, a plotrepresenting a theoretical path of an aircraft, and in that the flightmanagement system scrolls the time axis in such a way as to maintain ata fixed position on the screen an abscissa representing the time at theinstant of display.

This abscissa is preferably that of the origin of the axes, that is tosay that of the intersection of the abscissa and ordinate axes.Preferably, the altitude scale remains fixed, for a given portion ofpath, but provision may also be made for the system to scroll thealtitude axis in such a way as to maintain at a fixed position on thescreen an ordinate representing the actual altitude of the aircraft atthe relevant instant. This ordinate of fixed position is likewisepreferably that of the intersection of the axes.

Consequently, in the process according to the invention, the verticalflight plan is displayed as a function of the actual time rather than asa function of distances with respect to the waypoints. The positions ofthe waypoints can be indicated on the plot of the path or on theabscissa axis, at abscissae corresponding to the estimated instants oftransit through these waypoints.

The invention also proposes a device for aiding aerial navigation usinga flight management system which carries out a dialogue with the pilotby means of several interfaces which include at least one displayscreen, characterized in that it comprises means for displaying on thescreen a time-graduated abscissa axis, an altitude-graduated ordinateaxis, and, in this system of axes, a plot representing a theoreticalpath of an aircraft, means being provided for scrolling the time axis insuch a way as to maintain at a fixed position on the screen an abscissarepresenting the time at the instant of display. Means may also beprovided for scrolling the altitude axis in such a way as to maintainfixed on the screen an ordinate representing the actual altitude of theaircraft at this instant.

This process and this device allow the pilot better management of timeforecasting, also allowing better information regarding the air controland the airline with which the pilot is communicating, and enhancedpossibilities for informing passengers. The pilot's assessment of thetime forecasts is global and immediate and need no longer be done usingspecific function keys (except to obtain more accurate computations caseby case). This better time prediction is especially appropriate for theunderstanding of the risks of collision.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will emerge onreading the following detailed description which is given with referenceto the appended drawings, in which:

FIG. 1 represents the flight management system FMS and its peripherals;

FIG. 2 represents an example of a vertical flight plan according to theprior art;

FIG. 3 represents an example of a vertical flight plan displayed by theprocess according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The device for aiding navigation according to the invention constitutesa part of an overall aircraft monitoring system. This overall system,represented in FIG. 1, essentially comprises:

the flight management system or FMS, this being a computer 10 which canreceive various information, can calculate other information and canforward it to the pilot by means of dialogue interfaces;

sensors 12 distributed throughout the aircraft, including for examplenavigation instruments (IRS inertial units, etc.), various sensorsgiving information about the state of the aircraft, optionallyinstruments for communicating with the outside, all of these sensorsbeing linked to the flight management system;

the interfaces for carrying out a dialogue with the pilot, which arelinked to the computer 10, and which will mainly include:

a flight control unit or FCU which makes it possible, with the aid ofbuttons, to select for example the heading of the aircraft, or othersettings which have to be supplied to the management system;

a screen for displaying navigation information, ND ("NavigationDisplay"), for displaying maps, flight plans, etc.,

a primary flight display PFD for displaying an artificial horizon,altitudes of the aircraft, attitudes, velocity vectors, etc.,

a data display and input console or MCDU ("Multipurpose Control DisplayUnit").

The vertical flight plan according to the invention will be displayed inprinciple on the navigation display ND; this display operates under thedirect control of software contained in the FMS computer. The verticalflight plan will however not be displayed permanently on the navigationdisplay, but will be displayed in response to the activating of aspecific function key of the display.

In FIG. 2 may be seen a vertical flight plan displayed in a mannerproposed in the prior art (French Patent Application already cited). Theflight plan comprises a segment plot linking several points of transitrepresented by diamonds. Each diamond corresponds to a waypoint (WPT01to WPT04) positioned on the abscissa axis which is an axis graduated indistances. The projections of the waypoints onto the abscissa axis aredesignated by the letter R. The position of the aircraft at the relevantinstant is represented by an aircraft symbol at the start of the path.Triangular symbols pointing up (S1) and pointing down (S2) respectivelyrepresent minimum and maximum altitude constraints which the aircraftmust comply with during its journey. These constraints are generallyassociated with waypoints and are therefore located on the screen at thesame abscissa as the corresponding waypoint. Two head-to-tail triangleswhich touch at their tip therefore indicate a compulsory altitude oftransit (S3).

In the example represented, the path is split up into three parts, withdiverse altitude constraints:

I: climbing in altitude

II: cruising level

III: descent

FIG. 3 represents a display obtained with the means proposed by thepresent invention. This display can occupy the entire navigation displayND or just half; the display could also be produced on a screen otherthan the ND display.

The display comprises a horizontal time axis and a vertical altitudeaxis. The horizontal axis, or abscissa axis, is graduated in universaltime (UTC), along a scale which scrolls over time. In the simplestexample, scrolling is such that at each instant the origin of the timeaxis represents the current time at the moment of the display. In thegraph, it is 8H05 at the time of display and the time scale scrolls fromright to left. At 8.30 a.m. the display will be such that the graduation8H30 will have moved to the left until it takes the place of thegraduation 8H05 at the intersection of the abscissa axis and theordinate axis. Provision may be made for the abscissa representing thecurrent time to be a fixed point of the screen other than theintersection of the abscissa and ordinate axes, but it is moreconvenient to make provision for it to be this intersection.

The vertical axis, or ordinate axis, is graduated in terms of altitude.In the example represented, the graduation is defined in units of 100feet (one foot=30 cm approximately), that is to say the graduation 300corresponds to an altitude of 30,000 feet. The graduation can depend onthe flight phases: up to a transition altitude, the graduation is infeet; it is then in terms of flight level (FL), that is to say in unitsof 100 feet.

In this embodiment, the altitude scale also scrolls: the graduationsscroll downwards as the aircraft climbs, or scroll upwards as theaircraft descends, in such a way that the altitude of the aircraft atthe instant of display is maintained at a fixed point. In the examplerepresented, this fixed point is the intersection of the axes.

If the scales scroll in such a way that the point of intersection of theaxes simultaneously represents the current time and the current altitudeof the aircraft, it is understood that this point represents theposition of the aircraft in the reference system at the relevantinstant.

The flight plan is represented in this system of axes in the form ofstraight segments whose slopes represent the rates of climb and ofdescent, and whose horizontal plateaux represent the cruising altitudesbetween the periods of climb and/or of descent. Waypoints may beindicated in the form of diamonds on these segments. They are referencedWPT1 to WPT9 in the flight plan of FIG. 3. The waypoint WPT1 lying tothe left of the ordinate axis signifies that this point has already beenpassed at the time of display. It is not absolutely necessary for thatpart of the flight plan which has already been carried out to beretained on the left of the ordinate axis, but it is however convenientto have a small fraction of it which represents the part most recentlycarried out.

It is the flight management system FMS which computes the plot of thestraight segments to be displayed, from the theoretical flight plan dataentered by the pilot and from actual data delivered by the aircraft'ssensors, so that the vertical flight plan displayed does actuallycorrespond to that which is occurring at the relevant moment. Naturally,provision may also be made for the flight management system to deliveronly flight plan information and for the display terminal to be anintelligent terminal which is able to produce the plots from theinformation received.

It is understood that the position of a waypoint in the system of axesrepresents

along the ordinate the desired theoretical altitude of transit above thewaypoint,

and along the abscissa the forecast instant of transit above thiswaypoint.

The management system therefore continuously recomputes the points to bedisplayed, as a function of the path actually followed by the aircraft.

An aircraft symbol is placed at the point representing the current timeand the current altitude. This symbol is therefore placed in thisexample at the intersection of the time axis and the altitude axis. Itremains at this fixed position while the time and altitude scales arescrolling. The orientation of the drawing of the symbol of the aircraftcan turn about this position, so that this orientation represents theslope actually followed by the aircraft; the slope is the rate ofvariation of altitude per unit time; it can be computed by the flightmanagement system from the data delivered by the sensors. Thus, theaircraft symbol represents in a very readable manner the climb slope ofthe aircraft and it is easy for the pilot to check that the tilt of thesymbol corresponds to the slope of the plot of the flight plan segmentdisplayed at a given moment.

It may be preferable for the altitude scale not to scroll while theaircraft is climbing; in this case, the aircraft symbol displayed staysput at the abscissa 0 (representing the current time), but it movesalong the ordinate axis as the aircraft climbs or descends. Itsorientation remains parallel to the current climb slope.

The symbol of the aircraft can be a symbol such as that represented inFIG. 3, representing a horizontal schematic view of the aircraft, orelse a symbol representing a lateral schematic view of the aircraft.

The vertical flight plan thus displayed can comprise other indications,and most especially altitude constraints at the waypoints or altitudeconstraints during horizontal cruising. The altitude constraints at thewaypoints could be represented by triangles pointing up or pointing downsuch as those of FIG. 2.

In the example represented, the following information appears on thescreen:

the altitude safety margins (REC MAX alt) which are not to be exceeded,and/or the optimum flight altitude (OPT alt) computed by the flightmanagement system as a function of predefined criteria, as well as thealtitude clearance (FCU alt) permitted by air control and adjusted bythe pilot on the FCU interface;

the value of the wind at the waypoints, in the form of symbols whichdepend on the strength of the wind and whose orientation depends on thedirection of the wind;

the safety altitudes for the various phases of the flight; in FIG. 3,this is the staircase curve appearing at the bottom of the figure, whichis split up into minimum-altitude plateaux (altitude referenced withrespect to the graduation of the ordinate axis) for each segment of thevertical flight plan; the symbol of the aircraft must always be abovethis safety altitude; the safety altitudes are stored in a data basemanaged by the flight management system.

The altitude clearance FCU alt could flash and/or change colour in theevent of the presence of another aircraft at a difference of less than1000 feet (300 m), this in the case in which a presence detection systemis provided or if radio data indicating this information are received bythe flight management system. An audible alarm and an indication of theexact value of the vertical deviation could be given.

Preferably, a time marker which serves to define a time reference with aview to an action to be performed at the time indicated by this markermay be made to appear on the abscissa axis. When the time scale scrolls,the marker will approach the origin of the axes, and an alarm orspecific indication (flashing, luminous signal on the screen or off thescreen, audible warning, etc.) could be triggered by the flightmanagement system when the marker reaches the origin. Naturally, severalmarkers may be provided simultaneously at different times. In aconvenient embodiment, the pilot acts on a touchpad in order to move acursor along the time axis and "clicks" when the cursor is over thedesired time position so as to create and display the time marker.

Function keys are provided around the viewing screen for specialfunctions of this type which are related to the temporal display of thevertical flight plan. Thus, for example, the "TIME MARKER" function keysituated on the right of the screen makes it possible, if it isdepressed, to activate this marker creation function without modifyingthe display of the vertical flight plan.

The other function keys make it possible to carry out additionalfunctions such as flight plan revision, display of the ground speed ofthe aircraft, etc.

The function keys on the left of the screen are keys CSTR ALT, CSTR SPD,CSTR TIME allowing the pilot to re-input constraints relating toaltitude, to speed and to time respectively. The STEP key makes itpossible to schedule a climb or a descent in the cruising phase for along-haul flight.

The keys on the right of the screen make it possible to access thefollowing functions:

PRED TO ALT: gives the time of transit at a specified altitude;

PRED SPD: allows the display of predictions of speed over the whole ofthe flight plan or over a particular waypoint;

REPLAN: displays the 5 closest airports and gives the possibility ofcomputing predictions of time of arrival for each.

These keys are given merely by way of example; the REPLAN key could beassociated with the lateral flight plan rather than with the verticalflight plan.

Generally, the lateral flight plan modification functions will pass onthe changes (via the flight management system) to the vertical flightplan, and vice versa.

What is claimed is:
 1. Process for aiding aerial navigation, using aflight management system which carries out a dialogue with the pilot bymeans of several interfaces which include at least one display screen,characterized in that the flight management system displays on thescreen a time-graduated abscissa axis, an altitude-graduated ordinateaxis, and, in this system of axes, a plot representing a theoreticalpath of an aircraft, and in that the flight management system scrollsthe time axis in such a way as to maintain at a fixed position on thescreen an abscissa representing the time at the instant of display. 2.Process according to claim 1, characterized in that the abscissa offixed position representing the time at the instant of display issituated at the intersection of the abscissa and ordinate axes. 3.Process according to claim 2, characterized in that the flightmanagement system scrolls the altitude axis in such a way as to maintainat a fixed position on the screen an ordinate representing the actualaltitude of the aircraft at the relevant instant.
 4. Process accordingto claim 2, characterized in that the plot of the path comprises symbolscorresponding to characteristic points, the abscissa of these symbolsbeing the forecast instant of transit above these points.
 5. Processaccording to claim 2, characterized in that the flight management systemdisplays a time marker on the scrolling abscissa scale and in that itactivates an alarm when the time marker reaches the origin of the axes.6. Process according to claim 2, characterized in that the flightmanagement system controls the calculation and display of an aircraftsymbol placed on the screen at a position representing the current timeand the current altitude of the aircraft.
 7. Process according to claim1, characterized in that the flight management system scrolls thealtitude axis in such a way as to maintain at a fixed position on thescreen an ordinate representing the actual altitude of the aircraft atthe relevant instant.
 8. Process according to claim 7, characterized inthat the ordinate of fixed position representing the actual altitude issituated at the intersection of the abscissa and ordinate axes. 9.Process according to claim 8, characterized in that the plot of the pathcomprises symbols corresponding to characteristic points, the abscissaof these symbols being the forecast instant of transit above thesepoints.
 10. Process according to claim 8, characterized in that theflight management system displays a time marker on the scrollingabscissa scale and in that it activates an alarm when the time markerreaches the origin of the axes.
 11. Process according to claim 8,characterized in that the flight management system controls thecalculation and display of an aircraft symbol placed on the screen at aposition representing the current time and the current altitude of theaircraft.
 12. Process according to claim 7, characterized in that theplot of the path comprises symbols corresponding to characteristicpoints, the abscissa of these symbols being the forecast instant oftransit above these points.
 13. Process according to claim 7characterized in that the flight management system displays a timemarker on the scrolling abscissa scale and in that it activates an alarmwhen the time marker reaches the origin of the axes.
 14. Processaccording to claim 7, characterized in that the flight management systemcontrols the calculation and display of an aircraft symbol placed on thescreen at a position representing the current time and the currentaltitude of the aircraft.
 15. Process according to claim 1,characterized in that the plot of the path comprises symbolscorresponding to characteristic points, the abscissa of these symbolsbeing the forecast instant of transit above these points.
 16. Processaccording to claim 15, characterized in that the flight managementsystem displays a time marker on the scrolling abscissa scale and inthat it activates an alarm when the time marker reaches the origin ofthe axes.
 17. Process according to claim 1, characterized in that theflight management system displays a time marker on the scrollingabscissa scale and in that it activates an alarm when the time markerreaches the origin of the axes.
 18. Process according to claim 1,characterized in that the flight management system controls thecalculation and display of an aircraft symbol placed on the screen at aposition representing the current time and the current altitude of theaircraft.
 19. Process according to claim 1, further comprisingdisplaying safety altitudes for corresponding to segments of saidtheoretic path of said aircraft.
 20. Device for aiding aerial navigationusing a flight management system which carries out a dialogue with thepilot by means of several interfaces which include at least one displayscreen, characterized in that it comprises means for displaying on thescreen a time-graduated abscissa axis, an altitude-graduated ordinateaxis, and, in this system of axes, a plot representing a theoreticalpath of an aircraft, means being provided for scrolling the time axis insuch a way as to maintain at a fixed position on the screen an abscissarepresenting the time at the instant of display.
 21. Device according toclaim 20, characterized in that means are provided for scrolling thealtitude axis in such a way as to maintain fixed on the screen anordinate representing the actual altitude of the aircraft at the instantof display.
 22. Device according to claim 8, further comprising meansfor displaying safety altitudes for segments of said theoretical path ofsaid aircraft.